Battery Compartment Questions

Hi everybody. I just got a KWA HK G36C and I realized it didn't come with a battery. I'd like a Li-Po battery but I'm a bit stuck on the size. I know the battery compartment is listed as 92mm x 28.6mm x 15.9mm but I was wondering if a battery that was 107mm x 35mm x 21mm would fit, preferably with modification to the gun. If it needs to be modified just let me know what I would need to do.